Cometh forth to the water - See the Exodus 7:15 note. It is not improbable that on this occasion Pharaoh went to the Nile with a procession in order to open the solemn festival, which was held 120 days after the first rise, at the end of October or early in November. At that time the inundation is abating and the first traces of vegetation are seen on the deposit of fresh soil.

The plague now announced may be regarded as connected with the atmosphere, also an object of worship.

And the Lord said unto Moses, rise up early in the morning,.... Of the day following, the twenty eight of Adar, or February, according to Bishop Usher; this was the fittest time to meet with Pharaoh, and the most likely to make impressions on him:

and stand before Pharaoh: meet him as he comes along, and stop him, and stand before him as having something to say to him; this was using great boldness and freedom with a king; but as Moses was ordered to do it by the King of kings, it became him to obey him:

lo, he cometh forth to the water; See Gill on Exodus 7:15.

and say unto him, thus saith the Lord, let my people go, that they may serve me; which had often been required before, but to no purpose, and in case of refusal he is threatened as follows.

As the Egyptian magicians saw nothing more than the finger of God in the miracle which they could not imitate, that is to say, the work of some deity, possibly one of the gods of the Egyptians, and not the hand of Jehovah the God of the Hebrews, who had demanded the release of Israel, a distinction was made in the plagues which followed between the Israelites and the Egyptians, and the former were exempted from the plagues: a fact which was sufficient to prove to any one that they came from the God of Israel. To make this the more obvious, the fourth and fifth plagues were merely announced by Moses to the king. They were not brought on through the mediation of either himself or Aaron, but were sent by Jehovah at the appointed time; no doubt for the simple purpose of precluding the king and his wise men from the excuse which unbelief might still suggest, viz., that they were produced by the powerful incantations of Moses and Aaron.

Exodus 8:20-22

The fourth plague, the coming of which Moses foretold to Pharaoh, like the first, in the morning, and by the water (on the bank of the Nile), consisted in the sending of "heavy vermin," probably Dog-Flies. ערב, literally a mixture, is rendered κυνόμυια (dog-fly) by the lxx, πάμμυια (all-fly), a mixture of all kinds of flies, by Symmachus. These insects are described by Philo and many travellers as a very severe scourge (vid., Hengstenberg ut sup. p. 113). They are much more numerous and annoying than the gnats; and when enraged, they fasten themselves upon the human body, especially upon the edges of the eyelids, and become a dreadful plague. כּבד: a heavy multitude, as in Exodus 10:14; Genesis 50:9, etc. These swarms were to fill "the houses of the Egyptians, and even the land upon which they (the Egyptians) were," i.e., that part of the land which was not occupied by houses; whilst the land of Goshen, where the Israelites dwelt, would be entirely spared. הפלה (to separate, to distinguish in a miraculous way) is conjugated with an accusative, as in Psalm 4:4. It is generally followed by בּין (Exodus 4:4; Exodus 11:7), to distinguish between. עמד: to stand upon a land, i.e., to inhabit, possess it; not to exist, or live (Exodus 21:21).

And the LORD said unto Moses, Rise up early in the morning, and stand before Pharaoh; lo, he cometh forth to the water; and say unto him, Thus saith the LORD, Let my people go, that they may serve me.

8:20 Rise up early - Those that would bring great things to pass for God and their generation must rise early, and redeem time in the morning. Pharaoh was early up at his superstitious devotions to the river; and shall we be for more sleep, and more slumber, when any service is to be done which would pass well in our account in the great day?

Ex 8:20-32. Plague of Flies.

20-24. Rise up early . Pharaoh; lo, he cometh forth to the water, &c.-Pharaoh still appearing obdurate, Moses was ordered to meet him while walking on the banks of the Nile and repeat his request for the liberation of Israel, threatening in case of continued refusal to cover every house from the palace to the cottage with swarms of flies-while, as a proof of the power that accomplished this judgment, the land of Goshen should be exempted from the calamity. The appeal was equally vain as before, and the predicted evil overtook the country in the form of what was not "flies," such as we are accustomed to, but divers sorts of flies (Ps 78:45), the gad fly, the cockroach, the Egyptian beetle, for all these are mentioned by different writers. They are very destructive, some of them inflicting severe bites on animals, others destroying clothes, books, plants, every thing. The worship of flies, particularly of the beetle, was a prominent part of the religion of the ancient Egyptians. The employment of these winged deities to chastise them must have been painful and humiliating to the Egyptians while it must at the same time have strengthened the faith of the Israelites in the God of their fathers as the only object of worship.

8:20-32 Pharaoh was early at his false devotions to the river; and shall we be for more sleep and more slumber, when any service to the Lord is to be done? The Egyptians and the Hebrews were to be marked in the plague of flies. The Lord knows them that are his, and will make it appear, perhaps in this world, certainly in the other, that he has set them apart for himself. Pharaoh unwillingly entered into a treaty with Moses and Aaron. He is content they should sacrifice to their God, provided they would do it in the land of Egypt. But it would be an abomination to God, should they offer the Egyptian sacrifices; and it would be an abomination to the Egyptians, should they offer to God the objects of the worship of the Egyptians, namely, their calves or oxen. Those who would offer acceptable sacrifice to God, must separate themselves from the wicked and profane. They must also retire from the world. Israel cannot keep the feast of the Lord, either among the brick-kilns or among the flesh-pots of Egypt. And they must sacrifice as God shall command, not otherwise. Though they were in slavery to Pharaoh, yet they must obey God's commands. Pharaoh consents for them to go into the wilderness, provided they do not go so far but that he might fetch them back again. Thus, some sinners, in a pang of conviction, part with their sins, yet are loth they should go very far away; for when the fright is over, they will turn to them again. Moses promised the removal of this plague. But let not Pharaoh deal deceitfully any more. Be not deceived; God is not mocked: if we think to cheat God by a sham repentance and a false surrender of ourselves to him, we shall put a fatal cheat upon our own souls. Pharaoh returned to his hardness. Reigning lusts break through the strongest bonds, and make men presume and go from their word. Many seem in earnest, but there is some reserve, some beloved, secret sin. They are unwilling to look upon themselves as in danger of everlasting misery. They will refrain from other sins; they do much, give much, and even punish themselves much. They will leave it off sometimes, and, as it were, let their sin depart a little way; but will not make up their minds to part with all and follow Christ, bearing the cross. Rather than that, they venture all. They are sorrowful, but depart from Christ, determined to keep the world at present, and they hope for some future season, when salvation may be had without such costly sacrifices; but, at length, the poor sinner is driven away in his wickedness, and left without hope to lament his folly.